Do you own one of them? If so, are they informative?

I'd love to get ahold of one, but they are so elusive

I own the guide to RPGM 2... I use it when I use RPG Maker 2. It doesn't help me very much because it sounds like they are speaking a different language. Also, there are a few typos in the guide that if you are going by the guide can get you messed up.

I think that there is only one guide available. The PRIMA guide for 2. Did RPG Maker 1 have a guide? RPG Maker 3 doesn't.

RPGM1 didn't get a guide because it was a minor title at the time. RPGM3 didn't get one because it doesn't need it.

The RPGM2 guide, IMO, isn't really that informative. Except for the index in the back that shows all the preset maps, dungeons, buildings, building/dungeon textures, map textures, objects, characters, and enemies. It doesn't show anything that's available in the VFX editor, though.